This invention relates to a vehicle window antenna mounted on a surface of a glass fit in a window frame of a vehicle such as automobile.
Japanese utility model application laid open to public as Kokai Sho-61-197714 discloses a vehicle window antenna of this kind comprising a single antenna element in the from of a strip conductor extending generally alongside a frame of a rear quarter window of an automobile. The length of the antenna strip conductor as well as the distance thereof from the window frame are chosen such that the maximum antenna gain is attained at the center of the desired frequency band, e.g., very high frequency (VHF) band.
With this arrangement, the antenna always provides a relatively high Q factor causing the antenna gain to fall rapidly as the frequency goes farther away from the center point of the maximum gain. Therefore, it is not suitable for a broad-band radio receiver. To state it in another way, such a receiver would require an expensive tuner circuit which can compensate for the antenna characteristics.
It is therefore an object of the invention to provide a vehicle window antenna which overcomes these disadvantages.